Electrostatic paint spraying apparatus for changing liquids



Aug. 25, 1964 H. HERKLOTZ ETAL 3,145,930

APPARATUS FOR CHANGING ELECTROSTATIC PAINT SPRAYING LIQUIDS Filed Jan.5, 1961 5 Sheets-Sheet 1 HEL MUT HER/(072, LOU/5 arm, WAL TER LE/CHTLE,WALT'R PLATZ, HEKBERT W/EGELMA/V/V W :tarney:

Aug. 25, 1964 H. HERKLOTZ ETAL 3,145,930

APPARATUS FOR CHANGING ELECTROSTATIC PAINT SPRAYING LIQUIDS 5Sheets-Sheet 2 Filed Jan. 5, 1961 .[nVe/nm l/E'L/Ml/Tf/EKKZOTZ, 00150770, WAL TER LE/CH 7/. E, WAL 76/? PZATZ B Y HERBERT W/EGEL MAN V f MAitarne'y Aug. 25, 1964 H. HERKLOTZ ETAL APPARATUS FOR CHANGINGELECTROSTATIC PAINT SPRAYING LIQUIDS Filed Jan. 5, 1961 5 Sheets-Sheet 5.[I7VE/7L0/S z, LOU/S 0770 75? LE/CHTLL-j. WALTERPtATZ, HEABEKT WlEGELM/l/V N I Attorney HELMUT HER/(107' WA 25, 1964 H. HERKLOTZ ETAL 3,

" APPARATUS FOR CHANGING ELECTROSTATIC PAINT SPRAYING LIQUIDS Filed Jan.5, 1961 5 Sheets-Sheet 4 J n v en in rs HELMUT HERKLOTZ, LOU/5 OT T 0WALTER LE/CHTLE, WALTER PLATZ HERBERT W/EGELMANN BY A 7ORNE 5 Aug. 25,1964 H. HERKLOTZ ETAL 3,145,930

APPARATUS FOR CHANGING ELECTROSTATIC PAINT SPRAYING LIQUIDS 5Sheets-Sheet 5 Filed Jan. 5, 1961 Invemors HELMUT HER/(L0 TZ, LOU/S arm,WALTER 15/0 n 72,

Y 7 Attorneys E, WALTER PLA HERBER T W/EGEL MA MA BY United StatesPatent "ice 3,145,930 ELECTROSTATIC PAINT SPRAYING APPARATUS FORCHANGING LIQUIDS Helmut Herklotz and Walter Leichtle, Neu-Isenburg, andLouis Otto, Walter Platz, and Herbert Wiegelmann, Frankfurt am Main,Germany, assignors to Metallgesellschaft Aktiengesellschaft, Frankfurt,Germany Filed Jan. 5, 1961, Ser. No. 80,944 Claims. (Cl. 239-15) Thisinvention relates to a device for changing or switching liquids. Inparticular, the invention is directed to the changing of a liquid in apaint or lacquer spraying device in order to change the color beingsprayed.

In paint spraying apparatuses, it is desirable to spray various colorsone after the other from the same spray nozzle. Such a change in thecolor of the liquid entails the necessity of cleaning the pipe linesbetween each color change. Existing devices utilize switching devices ormultichannel feeders for changing from one color to another. Suchdevices are complicated and have angular passages which are difficult toclean. The instant invention has for its object the changing of thecolor of the paint or the like by a rapid and automatic switching means.According to this invention, the change from one color to another iscarried out, including the flushing or the rinsing of the pipe lines,within one minute. The invention provides for the cleaning of the pump,pipes and hoses and the spray nozzles by rinsing them after one colorhas been sprayed and in preparation for spraying a different color. Theapparatus of this invention has the advantage in that it can beinstalled in existing apparatuses because it requires very little space.

This invention is especially adapted for paint and lacquer changes in anelectrostatic spraying apparatus and is distinguished in that thedistributor or color selector head for the liquid paint or lacquer andthe paint pump are mutually mounted upon a bracket which is spaced froma supporting frame or stand by means of insulators, and with the headand pump being driven through insulating shafts. The stand or framesupports a gear unit, a potentiometer, and a selector headbrush-shifting drive motor, which drives the gear unit, and a drivemotor for the pump.

In the spraying booth, the selector head should be located as closely aspossible to the spray nozzle. The pump is driven through an insulatedshaft by a tightly coupled polyphase induction motor running at about1500 rpm. Also, the pump can be driven by a conventional driving motorhaving a low variable speed. When driven at a low variable speed, thearmature of the high speed motor is dead and rotates idly. When the highspeed motor is activated, then the low speed motor is cut off by meansof a freely overrunning clutch with which the two motors are coupled.During spraying time, the low variable speed motor drives the pump byitself. During change-over from one color to another, the use of thehigh speed motor results in a shortened pumping time during the flushingor rinsing of the pipe lines and the advancing of a fresh paint to thespray nozzle. The high speed motor is then cut out and the low variablespeed motor actuated to drive the pump.

The selector or control distributor head is composed of a cylindricalhousing having radially extending openings therethrough with pipeconnection fittings and a valve plug body rotatably mounted in thehousing. This body has an axially extending passage which communicateswith a radially extending passage, with the latter being adapted to bealigned with one of the radial openings in the housing. The selectorhead is coupled to an electric potentiometer driven by a motor. Theselec- 3 ,145,930 Patented Aug. 25, 1964 tor head is connected by tubesjoined to the pipe fittings with the various paint holding tanks.

The apparatus is remotely controlled from a switching system. Thissystem contains the elements for automatically switching from one colorto another through a complete cycle. The manner of operating theswitching system is as follows:

A new color is selected by pressing a color selection switch on theelectric control panel upon which the following functions areautomatically performed: The color selector head is turned to thepassage to which the cleaning agent, such as a solvent or thinner, isjoined and the high speed pump motor is activated, upon which thesolvent is rapidly pumped through the selector head and spray nozzle toclean the same. After a predetermined flushing time, the selector headis turned automatically to the passage connected to the new colorsupply. The high speed motor rapidly pumps the new color liquid throughthe pipe system until all of the solvent in the pipes has been pushedout and the pipe system filled with the new color liquid. Then the highspeed motor cuts off and the low speed variable motor is activated topump the new color liquid through the spray nozzle. The switching systemhas the further feature of having a follow-up control for adjusting theselector head and the time sequence control for completing the liquidchanging process, so that these steps are automatically performed by oneand the same control means.

The means by which the objects of the invention are obtained aredescribed more fully with reference to the accompanying drawings, inwhich:

FIGURE 1 is a front elevational view of the apparatus;

FIGURE 2 is a plan view of FIGURE 1;

FIGURE 3 is a cross-sectional view through the selector head;

FIGURE 4 is a cross-sectional view taken on the line 4-4 of FIGURE 3;

FIGURE 5 is a circuit diagram of the switching system; and

FIGURE 6 is a circuit diagram for the entire apparatus.

As shown in FIGURES 1 and 2, a variable low speed motor 1 through atransmission gear 2 is connected by a coupling 3 and a free-Wheeloverrunning clutch 4 to the high speed scavenging or rinsing pump motor5. An insulating shaft 6 is connected by joints 7 to a pump 8 having aliquid feed inlet 9 and an outlet 10. Pump 8 is mounted upon a bracket11 which is suspended by means of a pair of insulators 12 from a standor frame 13. A flange connection 14 secures selector head 16 uponbracket 11. Selector head 16 is provided with a plurality of pipefittings 21 to which tubes are adapted to be attached, which tubes leadto the various paint color tanks 21a respectively. Selector head 16 isdriven through an insulating shaft 23 connected through joints 24 to agear unit 25 to which is coupled a potentiometer P1. The gear unit isdriven by a belt or chain drive 27 connected to an electric motor 28.

As shown in FIGURES 3 and 4, the selector head 16 is composed of acylindrical housing 36 having a plurality of radially extending passages37 into which the pipe couplings 21 are fitted. Rotatably mounted in thehousing is a valve plug body 39 in the shape of a truncated cone. Thisbody is rotated by a stub shaft 40 connected to insulating shaft 23. Theopposite side of body 39 is extended by means of a shaft having an axialbore 41. The shaft terminates in a fitting 42 adapted to be connected tothe inlet 9 of pump 8. This turnable extension is provided with aflanged collar 43 against which the spring 44 is pressed, with the otherend of the spring being held against spring seat 45. Plug body 39contains an axial passage 46 which communicates with a radial passage 47adapted to be aligned with one of the openings 37. Of the thirteenradial openings 37 which are shown, one is always connected to the tankholding the flushing or rinsing fluid, while the other openings areconnected to the various paint or lacquer tanks of diffierent colors,respectively. By turning plug 39, the passage 47 is lined up with thedesired opening 37.

As shown in FIGURE I, paint of a chosen color or rinsing fluid flowsfrom tank 21a through fitting 21, radial passage 47, axial passage 46,bore 41, and pipe 42a to pump inlet 9. The fluid leaves the pump 8through pipe 421) and is led to paint nozzle 58, from which the paint issprayed on an object such as the vehicle 59.

The wiring diagrams represented in FIGURES 5 and 6 contain the followingessential control element groups:

The follow-up control for adjusting selector head 16 (paint distributor)and the time-sequence control for handling the paint-changing cycle.

The function of the individual control elements becomes evident from thefollowing description of the wiring diagrams of FIGURES 5 and 6:

If a paint change is desired, then the paint selector switch LS is seton the paint color to be selected, such amounting to the switching ofcontact LS to the variable resistor which goes with same. Paint changingkey T1 is pressed by hand and cuts in relay D, FIGURE 5. By closingcontact d relay I is energized. The auxiliary contacts through jg arehereby activated; cuts out paint selector switch LS; j switches fixedtap for flushing fluid, W1, a potentiometer, in conjunction with paintselector switch setting means, to polarized relay A. Contact 1' switcheson paint change pilot lamp MLl. Relay responds simultaneously; contact 0is opened, and in doing so, the high-voltage that is placed on theterminals 56, 56 from the painting apparatus is switched off. Theclosing of contact 0 causes the controlling mechanisms which areconnected to terminals 57, 57' to set off switching processes by meansof which the spray nozzle 58 is brought to a definite position, forexample, pointed into a waste tank. Contact 1' opens, and switches offrelay D once more. Contact is closed and thus paves the way for thetripping process of the time circuit P3-C4 and contact trips the delayedcut-in relay F. Contact i bridges key T3, and contact j7 de-energizesrelay N. According to the way P1 is positioned, relay A will cause relayB or C to respond via contact a Motor switches G or H are switched invia b or 0 for the selector head motor 28. The field coils of motor 28are connected to terminals 50, 50 and the armature windings to 51, 51'.Capacitor C2 or C3 is switched in parallel fashion to relay B or C bycontact h or 0 (delayed release). By virtue of the full transformervoltage, motor 28 runs at high speed via contact i which is closed inthe normal position. Transformer Tr is energized via the terminals 49,49' with an alternating voltage of 220 volts.

Potentiometer P1 goes beyond the equalization with LS, and in so doingswitches over relay A. Again, through this, contact al switches fromrelay B to C, or else from C to B; correspondingly contacts b and 6cause contactor G or H to operate. Due to the delayed release of B or,as the case may be, C, relays B and C are both energized for a shorttimeand even the motor contactors G and H as well-by way of contacts band c Auxiliary contacts g and 11 short-circuit the armature winding ofthe motor 28 during this time, and by this means bring about the brakingof the motor 28. contacts g and 11 cause switch-over contactor S for themotors fast-slow speed to respond, whereby contact s cuts out theslow-acting capacitors C2 and C3. One of the two relays, B and C,releases, and in so doing release G and H as well. Contactor S is heldby way of contacts s and g or, as the case may be, I1 Contact s opensand switches off the motor 28 so that the latter no longer runs at highspeed, and contact s (transformer partial voltage) switches thebrush-shifting motor 28 to slow speed. Potentiometer P1 returns tobalance position; relay A becomes de-energized through this, and hence,so do contactors B, or else C, and G, or else H. In doing such, contactsg or else 11 cut out contactor S. Contacts g and h close simultaneously,and delayed cut-in relay F begins to act via m and 0 Contacts g and I1close simultaneosuly, and delayed cut-in relay F begins to act via m and0 Contacts g and 12.; close and brake the motor 28 by short-circuitingthe armature winding. Contact 1, closes and applies voltage to theexciting electrode of cathode tube Z803U via potentiometer P2, contact11; and capacitor C4 (timelimit relay switching). The voltage isdecreased by rectifier G11 on which an alternating voltage of 220 voltshas been placed by way of terminals 48, 48. Contact f closes and causesscavenging motor 5 to start up via switch M. The poly-phase motor ishooked up to terminals 55, 55', 55" as a scavenging motor, and atterminals 54, 54, 54" a three-phase voltage is drawn from the powersupply. After contactor M breaks, the threephase windings areshort-circuited, and the motor braked.

After a specified period of time (setting at potentiometer P2) tubeZ803U lights up and relay E begins to act. This causes contact 6 to cutin relay D, and contact e discharges capacitor C4 via resistor R10. Byopening contact d relay J functions and hence, so do relays F and M dueto the opening of contacts and 11;. Switch d causes contactor K torespond; contact k switches the preselected tap of paint selector switchLS to relay A; contactor k continues to keep the circuit to pilot lampMLl closed and holds the circuit for contactor 0. Contact k de-energizesrelay D due to its opening, and contact k prepares the cut-in of thetime-base circuit P3-C4 (timing at P3). Contact k cuts in slow-actingrelay F; contact k bridges key T3, and contact k cuts out relay N.Change-over contact a switches to relay B or C according to the Way theoperation is set up, and auxiliary contact of sameb or c causes selectorhead motor 28 to start up via motor contactor G or, as the case may be,H. Switch b switches capacitor C2 in parallel fashion to relay B or, asthe case may be, contact c switches capacitor C3 in parallel fashion torelay C (releasing delay). The motor again runs at high speed.

Motor 28 is now shifted from high to low speed through the circuitryheretofore described and stopped.

Following the fixed time P3C4, relay E begins to act via the electrontube Z803U. This causes contact e to cut in relay D which produces ashift on the part of selector switch LS. Contact e again dischargescapacitor C4. Contacts d and m cause contactor relay L to respond fornormal paint pumping operation, in which case contact l causes the pilotlamp ML2 to light up; contact closes and bridges contact m so that relayL itself is held. The lacquer pump motor 1 is hooked up to terminals 53,53, 53". The connections to the threephase line are at terminals 52, 52,52". By cutting out relay D, relay K is released-as are also relays F,M, O via contacts k k and k7; pilot lamp MLl is also extinguished.

The switching operation for general flushing, rinsing or cleaning is asfollows:

Key T2 (general cleaning) is pushed by hand and causes contactor N torespond. This causes a series of switching operations to be triggeredonce again. Contact 12 switches the flushing switch at W1 to relay A.Due to the opening of contact 11 the possibility of a switching from T1is avoided, as is likewise a further switching of relay D. Contact 11cuts out relay E, and contact 11.; energizes delayed cut-in relay F.Contact n cuts out contactor L, and contact 11 holds contactor N itself.Contact 11 causes contactor O to take effect again which shuts off thehigh voltage and causes the sprayer to be protected. in which casecontact It breaks the power supply to pilot lamp MLl. In place of this,pilot lamp ML3, general cleaning, lights up via contact u According tothe way in which potentiometer P1 is positioned, contact a again cuts inrelay B or C, and it cuts in contactor G or H via contact b or elseContact b or provides for a delayed release of relay B or C again viacapacitor C2 or C3. The additional switching operations proceed asheretofore described.

After potentiometer P1 has gone to the balance position, relay A cutsout, and in doing so, relay B or C follows suit. Even relay S cuts outas well, provided that G and H were energized as a result of the delayedre lease of B and C. As rest contacts, contacts g and h cause relay F totake effect by Way of the tripping delay, and contacts g and kshort-circuit the armature Windings from terminals 51, 51 of theselector head motor 28. Contact f causes scavenging motor 5 to start upvia contactor M. The flushing operation can be interrupted by pressingkey T3, general cleaning, (switch-01f). By doing such, contactors M andN are cut out and relay F along with pilot lamp ML3 become de-energized.

Rectifiers G12 and G13 of a known design are still needed besidesrectifier G11. R11 is a current-limiting series resistor for transformerTr.

Having now described the means by which the objects of the invention areobtained, we claim:

1. In an electrostatic paint spraying apparatus, means for changing fromone spray liquid to another comprising a bracket, a liquid selector headand a liquid pump mounted upon said bracket, a spray nozzle adapted tobe electrically energized connected through said pump to said selectorhead, insulators for holding said bracket, a high speed motor connectedby an insulated shaft to said liquid pump for driving said pump to pumprinsing liquid to said selector head, an overrunning clutch joined tosaid high speed motor, a slow variable speed motor connected throughsaid clutch to said high speed motor for driving said liquid pump whilespraying paint, and a selector head insulated drive shaft joined to saidselector head.

2. In an apparatus as in claim 1, a supporting frame joined to saidinsulators, a selector drive motor coupled to the selector head shaftthrough a gear unit and a potentiometer and being mounted on said frame,and both the high and the slow speed pump drive motors being mounted onsaid frame.

3. In an apparatus as in claim 2, said selector head comprising acylindrical housing adapted to be connected to a high voltage source, aplurality of radially extending openings through said housing, a valveplug body rotatably mounted in said housing and joined to said selectorhead drive shaft, an axial passage in said body, and a radial passage insaid body communicating with said axial passage and being adapted to bealigned with one of said openings.

4. In an apparatus as in claim 3, said potentiometer being connected tosaid gear unit as an actual value transmitter of a follow-up control.

5. In an apparatus as in claim 1, said selector head and said liquidpump with their respective associated drives, being verticallyseparated.

References Cited in the file of this patent UNITED STATES PATENTS1,857,084 Goetz May 3, 1932 2,178,559 Cohen Nov. 7, 1939 2,189,950 GumpFeb. 13, 1940 2,250,507 Thomas July 29, 1941 2,257,004 Fleming Sept. 23,1941 2,272,544 Cederstrom Feb. 10, 1942 2,770,248 Audia Nov. 13, 19562,834,376 Hughes May 13, 1958 2,920,635 Wilson Jan. 12, 1960 2,921,599Fleischman Jan. 19, 1960 FOREIGN PATENTS 1,162,056 France Mar. 31, 1958

1. IN AN ELECTROSTATIC PAINT SPRAYING APPARATUS, MEANS FOR CHANGING FROMONE SPRAY LIQUID TO ANOTHER COMPRISING A BRACKET, A LIQUID SELECTOR HEADAND A LIQUID PUMP MOUNTED UPON SAID BRACKET, A SPRAY NOZZLE ADAPTED TOBE ELECTRICALLY ENERGIZED CONNECTED THROUGH SAID PUMP TO SAID SELECTORHEAD, INSULATORS FOR HOLDING SAID BRACKET, A HIGH SPEED MOTOR CONNECTEDBY AN INSULATED SHAFT TO SAID LIQUID PUMP FOR DRIVING SAID PUMP TO PUMPRINSING LIQUID TO SAID SELECTOR HEAD, AN OVERRUNNING CLUTCH JOINED TOSAID HIGH SPEED MOTOR, A SLOW VARIABLE SPEED MOTOR CONNECTED THROUGHSAID CLUTCH TO SAID HIGH SPEED MOTOR FOR DRIVING SAID LIQUID PUMP WHILESPRAYING PAINT, AND A SELECTOR HEAD INSULTED DRIVE SHAFT JOINED TO SAIDSELECTOR HEAD.